• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.5 s.110
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• pp.495-502
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• 2006

A fault diagnosis method is developed in this study using automaton through quantization of vibration signals for normal and faulty conditions, respectively. Automaton is a kind of qualitative model which describes the system behaviour at the level of abstraction. The system behavior was extracted from the probability of the output sequence of vibration signals. The sequence was made as vibration levels by reconstructing the originally measured vibration signals. As an example, a fault diagnosis for the bearing of ATM machine was done, which detected the bearing fault with confident level compared to any other existing methods of kurtosis or spectrum analysis.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.664-665
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• 2015

최근 IT기술이 점점 발달함에 따라 장애인의 일상생활을 편리하게 하는 도구들이 속속 개발되고 있다. 본 연구에서는 시각장애인들이 색상판별을 진동을 통해 감지할 수 있는 시스템을 개발하였다. 이것은 최근 대중화되고 있는 사물인터넷(IoT)의 기반이 되는 아두이노 기술을 접목하여 다양한 스위치와 센서로 입력 값을 받아들여 LED, 모터와 같은 외부출력장치를 제어함으로써 상호 작용을 만들어 낼 수 있는 시스템이다. 구체적으로 제안하는 시스템은 컬러센서를 통해 색상을 감지하고 색상 값을 수치 값으로 읽어 들이고 수치 값에 진동의 세기 주기 등을 달리함으로 시각장애인이 색상을 판별할 수 있도록 되어있다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.795-798
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• 2010

본 논문에서는 상사진동에서의 응답을 통해 구성된 모드유연도에 의해 추정되는 손상유발 변위를 이용하여 전당빌딩의 손상을 탐지하는 진동기반의 손상탐지 방법을 제시하였다. 이 방법은 전단빌딩의 층간변위를 활용하여 오직 손상이 존재할 때에만 발생하는 Damage-induced inter-story deflection (DI-ID)을 통해 손상탐지를 수행하는 방법이다. 구조물의 전체 자유도에 양의 전단력을 발생시킴으로써 층간변위를 분명히 파악할 수 있도록 하는 양전단력 탐색하중(Positive Shear Inspection Load)을 통해 DI-ID를 산정한다. 제안된 방법의 검증을 위해 5층의 전단빌딩 축소모형을 대상구조물로 선정하여 수치모의실험을 수행했다. 단일손상과 다중손상의 모사를 위해 1층과 3층의 휨강성을 각각 10% 씩 저감시켰고, 수치모의실험 결과, 단일손상과 다중손상 모두 정확히 손상발생 구역을 확인했다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.7
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• pp.665-673
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• 2011

Simplified formulae for axial and bending natural frequencies of a bellows are developed using an equivalent thin-walled pipe model. The axial and bending stiffness of bellows is determined using lumped transfer matrix method. Transfer matrix method which includes the rotary inertia is used to calculate the natural frequencies for axial and lateral vibration. The result from the simplified formula are verified by those from as experiment result and a finite element analysis. This comparisons show good agreement with the each other.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.346-353
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• 2013

Industrial processes need to be monitored in real-time based on the input-output data observed during their operation. Abnormalities in an induction motor should be detected early in order to avoid costly breakdowns. To early identify induction motor faults, this paper effectively estimates spectral envelopes of each induction motor fault by utilizing a linear prediction coding (LPC) analysis technique and an expectation maximization (EM) algorithm. Moreover, this paper classifies induction motor faults into their corresponding categories by calculating Mahalanobis distance using the estimated spectral envelopes and finding the minimum distance. Experimental results shows that the proposed approach yields higher classification accuracies than the state-of-the-art approach for both noiseless and noisy environments for identifying the induction motor faults.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.6
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• pp.821-826
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• 2013

When the values of design variables change, mode switching can often occur. If the mode of interest is not tracked, the frequencies and modes for design optimization may be miscalculated owing to modes that differ from the intended ones. Thus, mode tracking must be employed to identify the frequencies and modes of interest whenever the values of design variables change during optimization. Furthermore, reliability-based design optimization (RBDO) must be performed for design problems with design variables containing uncertainty. In this research, we perform RBDO considering the mode tracking of a compressive coil spring, i.e., a component of the joint spring that supports a compressor, with design variables containing uncertainty by using only kriging metamodels based on multiple responses approach (MRA) without existing mode tracking methods. The reliability analyses for RBDO are employed using kriging metamodel-based Monte Carlo simulation.

• Therapeutic Science for Rehabilitation
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• v.7 no.3
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• pp.23-33
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• 2018

Objective : This systematic review aimed to investigate the effect of focal muscle vibration in patients with post-stroke spastic hemiplegia. Methods : We searched literature published between April 2009 and October 2017 using PubMed and RISS databases. The main search terms were Vibration therapy, Focal vibration, Somatosensory, Upper limb, and Spasticity after stroke. Based on inclusion/exclusion criteria, 6 articles were selected. Results : Articles on focal muscle vibration intervention ranged from evaluation of application-only vibration to muscle vibration with task-oriented activity. Intervention effects on upper extremity spasticity and function and activities of daily living were assessed. There were significant effects on upper extremity spasticity, function, and cortical excitability. Conclusions : This study can provide information on focal muscle vibration for use by clinical therapists. However, further studies are needed to identify the optimal stimulation site and frequency/amplitude of application to maximize the effects of focal muscle vibration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.602-603
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• 2008

The design modification of problematic component in a given vibration path is disallowed in order to sacrifice other performances such as ride comport or handling of a vehicle. For this, the paper presents a new contribution analysis based on transmissibility ratio (TR) of acceleration in a definite vibration path to find a proper candidate for design modification. The new contribution analysis is based on the fact that the sensitivity of TR over a small design change is inversely proportional to the magnitude of TR. The new methodology can significantly relieve efforts of time-consumming modal analysis for detail modal information. The theory of proposed contribution analysis is simulated with five-degree-of-freedom open vibration path and confirms that the contribution result is well matched with the variance of TR over a dynamic change on a vibration path.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.230-237
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• 2006

본 논문은 스포츠 방송의 몰입감 증대를 위한 진동촉감 제시 시스템 및 장치를 제안하며, 촉감 정보를 효과적으로 전달하기 위한 촉감제시 방법론 및 제어 알고리즘을 제안한다. 최근 디지털 컨텐츠의 전달에 있어 오감을 통한 정보 전달의 관심이 증대됨에 따라, 대중을 대상으로 다양한 정보를 전달하는 디지털 매체에서의 시청각과 더불어 촉감 제시의 역할과 중요성이 증대되었다. 따라서 본 논문에서는 실시간으로 동적인 현장 상황을 실감 있게 전달하는 스포츠 방송에서의 햅틱 효과와 역할 그리고 가능한 시나리오를 정의하고, 진동촉감 제시 장비를 설계하여 촉감 정보 표현에 대한 기초 연구를 수행하였다. 또한 제안된 촉감을 이용한 스포츠 방송 시나리오 중 축구 방송을 기반으로 사용자 촉감 인지 실험을 수행하였으며, 실험 결과를 바탕으로 축구 방송 시스템을 구축하여 실감방송 전시회 시연을 통해 진동촉감 시스템 및 촉감 제시 방법론을 검증하였다. 촉감이 인간의 오감 중 시청각 다음으로 정보를 인지하는 중요한 감각 체계인 만큼 많은 양의 정보를 대중에게 전달하는 방송 시스템에서 시청각과 더불어 효과적인 정보 전달 체계로써 기여할 것이라고 여겨진다.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.3
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• pp.585-590
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• 2012

In this paper, a system using vibrating wire sensor and zigbee wireless network has been implemented to monitor and manage the structure. The implemented strain controller drives vibrating wire sensor and computes strain from measuring frequency of the output signal. Temperature sensor is included to compensate strain by temperature. Using two axis acceleration sensor of strain controller can measure the direction of strain or deformation. To measure strain more effectively, wired and wireless communication function is included in this device. As results of experiments, it is shown that the developed system can be effectively applied to measure strain of the structure.